1. Field of the Invention
The present invention relates to a lighting device for a display device and a display device including a lighting device.
2. Description of the Related Art
In a display device having non-luminous optical elements as typified by a liquid crystal display device, a backlight device is provided on the backside of a display panel such as a liquid crystal panel, so as to illuminate the display panel (as shown in JP-A-2006-66360, for example).
JP-A-2006-66360 discloses a backlight assembly that includes lamps and a housing member for holding the lamps. In the backlight assembly thus including lamps and a housing member for holding the lamps, beat tones may be generated during dimming control of the lamps, due to the second and third harmonics of a dimming control frequency.
There are various theories as to how the beat tones are generated. For example, one of the theories suggests involvement of current leakage from the lamps to the housing member. That is, the beat tones may be generated by vibration of the housing member caused by leakage current from the lamps.
JP-A-2006-66360 discloses that bulging portions or recessed portions corresponding to the lamps are formed on the housing member in order to prevent current leakage between the lamps and the housing member. However, the beat tones cannot be reduced adequately even according to this construction. Moreover, if bulging or recessed portions are provided, the housing member may be prone to having increased thickness due to the bulging or recessed portions. This is a significant problem where thinning of liquid crystal display devices is required.